Question

Which of the following are solutions to 2x2 – 8x - 90? Select all that apply.

Answer 1

x=-5, x=9

Explanation:

we know that

The formula to solve a quadratic equation of the form

`ax^(2) +bx+c=0`

is equal to

`x=\frac{-b\pm\sqrt{b^(2)-4ac}} {2a}`

in this problem we have

`2x^(2) -8x-90`

equate to zero

`2x^(2) -8x-90=0`

so

`2=-1\\b=-8\\c=-90`

substitute in the formula

`x=\frac{-(-8)\pm\sqrt{-8^(2)-4(2)(-90)}} {2(2)}`

`x=\frac{8\pm√(784)} {4}`

`x=\frac{8\pm28} {4}`

`x=\frac{8+28} {4}=9`

`x=\frac{8-28} {4}=-5`

therefore

The solutions are x=-5, x=9